Fucoxanthin is a xanthophyll

Xanthophyll

Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos + phyllon , due to their formation of the yellow band seen in early chromatography of leaf pigments...

, with formula C₄₂H₅₈O₆. It is found as an accessory pigment

Pigment

A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...

 in the chloroplast

Chloroplast

Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...

s of brown algae

Brown algae

The Phaeophyceae or brown algae , is a large group of mostly marine multicellular algae, including many seaweeds of colder Northern Hemisphere waters. They play an important role in marine environments, both as food and for the habitats they form...

 and most other heterokont

Heterokont

The heterokonts or stramenopiles are a major line of eukaryotes currently containing more than 100,000 known species. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which are a primary component of plankton...

s, giving them a brown or olive-green color. Fucoxanthin absorbs light primarily in the blue-green to yellow-green part of the visible spectrum

Visible spectrum

The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...

, peaking at around 510-525 nm by various estimates and absorbing significantly in the range of 450 to 540 nm.

Some metabolic and nutritional studies carried out on rats and mice at Hokkaido University

Hokkaido University

Hokkaido University is one of the most prestigious universities in Japan. It can be seen in the several rankings such as shown below.-General Rankings:...

 indicate that fucoxanthin promotes fat burning within fat cells in white adipose tissue

Adipose tissue

In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...

 by increasing the expression of thermogenin

Thermogenin

Thermogenin is an uncoupling protein found in the mitochondria of brown adipose tissue . It is used to generate heat by non-shivering thermogenesis...

. There is one known double-blind placebo-controlled human study with fucoxanthin that has been published. The small study in obese women showed in an average 4.9 kg (10.8 lb) weight loss over a 16-week period.

It is non-stimulatory, unlike other compounds such as ephedrine

Ephedrine

Ephedrine is a sympathomimetic amine commonly used as a stimulant, appetite suppressant, concentration aid, decongestant, and to treat hypotension associated with anaesthesia....

 and yohimbine

Yohimbine

Yohimbine is an alkaloid with stimulant and aphrodisiac effects found naturally in Pausinystalia yohimbe . It is also found naturally in Rauwolfia serpentina , Alchornea floribunda , along with several other active alkaloids...

.